Narrowing Methods

We should keep in mind that Conan Doyle was a physician, and it is said that he modeled Holmes after a teacher who was famed as a great diagnostician (Booth, 2000). Certainly, the narrowing method used by Holmes is... 

MAS is normally applied concurrently with the dipole line-narrowing methods in order to eliminate the effects of CSA and provide true high resolution NMR spectra in the solid phase. For heteronuclear systems the combined method is usually referred to by the initials CP-MAS, and for homonuclear systems the acronym CRAMPS (combined rotation and multiple pulse spectroscopy) has been coined. 

Narrowed by adding an element or limitation to a previously recited element narrow claim can be dependent or independent. Adding a step narrows method claims. Adding an element to a closed (such as Markush Group) claim broadens, not narrows claim. 

Abundant spins with a high gyromagnetic ratio, e.g., protons, lead in the absence of line-narrowing methods to unresolved spectra described by the Hamiltonian of Equations (4.1) and (4.2). The only relevant observable is the spatial distribution of the polarization, P(r t). Using the master-equation approach (Equation (4.8)), the spatial evolution of the polarization is described by a random walk on a grid that can be approximated by a diffusion equation... 

So, in this section and in the last, we have discussed two line narrowing methods which are fairly difficult to implement in typical solids where the lines are quite broad to begin with. It turns out that a combination of both techniques, i.e., MAS and high power decoupling, can work quite well in reducing the linewidth because each technique reduces the linewidth enough to make it easier for the other technique to work. The sensitivity problem, due to the fact that the nucleus of interest is rare, still remains and will be addressed in the following section. 

To obtain this detailed structural information, it is necessary to enhance the resolution of the protein amide I band, which usually appears as a single broad absorbance contour (Figure 1). The widths of the overlapping component bands are often greater than the separation between the absorbance maxima of neighboring bands. Because the band overlapping is beyond instrumental resolution, several mathematical band-narrowing methods (i.e., resolution enhancement methods) have been developed to overcome this problem [11,50-52,54]. For studies of lyophilization-induced structural transitions, calculation of the second derivative spectrum is recommended [11]. This method is completely... 

Chmelka, B.R, Zwanziger, J.R Solid-State NMR Line Narrowing Methods for Quadrupolar Nuclei Double Rotation and Dynamic-Angle Spinning. Vol. 33, pp. 79-124 Clayden, N.J. Solid State NMR of Synthetic Polymers. Vol. 29, pp. 91-126 Cohen, J.S., see Kaplan, O. 

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